PEM fuel cell deuterium generator

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Bob Reite
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Re: PEM fuel cell deuterium generator

Post by Bob Reite »

I used some old medicine bottles and rubber stoppers for my system. The photos above show a fancy custom built system. There is more than one way to do it.
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Re: PEM fuel cell deuterium generator

Post by Rex Allers »

I haven't built a generator like this yet, but I have accumulated parts (PEM cell, plumbing, valves, etc.).

My thought for a buffer holding chamber for the gas was to use a small mylar balloon rather than these oil displacing chambers. My thought was that it would be easy to suck oil if you want to evacuate to keep the D2 as pure as possible, or even from the chamber vacuum if you aren't watching enough. Seemed to me the balloon could be evacuated without a problem.
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Rich Feldman
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Re: PEM fuel cell deuterium generator

Post by Rich Feldman »

My story is like Rex's. Got hydrocar kits from craigslist & ebay, etc. Have a couple of Mylar balloons, but have not yet experimented with how to seal them to tubing. Found an ebay vendor who regularly sells D2O packaged in 50 gram lots for $75. You get only 45 ml because the water is, uh, heavy.

Storage in balloons misses one benefit easily achieved with gas-over-liquid reservoirs. That's "overpressure" relief in the vacuum plumbing. In case electrolytic gas production stops, we don't want a strong vacuum to develop on the PEM cell. If a PEM were supported to withstand vacuum, then we could skip the reservoirs and very-low-flow restrictor. Simply adjust electric current to set the D2 flow. No great technical problem there. Electrolytic "hydrostik" refillers run PEMs with hundreds of psi on the hydrogen side., as discussed in another thread.

[edit] Can also avoid risk of vacuum on PEM cell, by having no plumbing that connects reservoir to fusor flow control and PEM cell at the same time.

I learned that there's a well analyzed geometric shape called "Mylar balloon". From the nominal balloon size (diameter of flat circles sealed around the edge) we could figure the maximum inflated volume. I have not yet done that exercise, nor measured the volume using real fluid. I think that tables for party helium show 18" balloons needing about 1/2 cubic foot.
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Richard Hull
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Re: PEM fuel cell deuterium generator

Post by Richard Hull »

A rather inexpensive device with hydrogen and oxygen tanks (reversable PEM) for those experimenters. Might be adapatable....modifiable?

https://fuelcellstore.com/downloads/drf ... torage.pdf

Want just the reversable cell?.....

https://www.fuelcellstore.com/horizon-m ... -fuel-cell

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Fusion is the energy of the future....and it always will be
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Re: PEM fuel cell deuterium generator

Post by Rex Allers »

On Richards two fuelcellstore links.

I've never seen the first one but it seems to have a lot of implementation that might be better done in ways that are more specific to meet our needs.

Second link is for a reversible device (can be a fuel cell or an electrolyser). I think we only really want to go in the electrolyser direction and the following link is slightly cheaper.
Horizon Mini PEM Electrolyzer
https://www.fuelcellstore.com/horizon-m ... ectrolyser

It's been several years since I looked into these things but I thought there might have been some advantage to the electrolyser for our intended use. Well there is a $6.50 advantage from prices listed today. Thought there was something I read once about differences that might matter, but couldn't swear to it and can't find it now.
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Mark Rowley
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Re: PEM fuel cell deuterium generator

Post by Mark Rowley »

Several of the Horizon PEM cell videos demonstrate gas collection in a syringe. If deuterium was collected in a large 100cc syringe, would the vacuum in a typical Fusor be sufficient to draw from it via a needle valve (resulting in the slow retraction of the plunger)? Or is it necessary that I have positive deuterium pressure?

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Bob Reite
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Re: PEM fuel cell deuterium generator

Post by Bob Reite »

The vacuum would be more than enough, you don't need pressure. In fact the PEM cell has to be protected from excessive positive or negative pressures.
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Re: PEM fuel cell deuterium generator

Post by Rich Feldman »

Rex Allers has one of the PEM cell electrolyzers for refilling storage cartridges.
Puts out H2 even against back pressures of more than 400 psi.

As I've said before, maybe even in this very thread, there's no technical reason a membrane couldn't be supported on the hydrogen side, to withstand full vacuum. Then fusor gas flow would be controlled directly and immediately by the electrolyzer current setting.
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Re: PEM fuel cell deuterium generator

Post by Martiname »

Hi All,

I would like to build fully automatic Deuterium generator with PEM Cell. To avoid any unnecessary liquid parts (vacuum oil) I going to use only pressure switch with Over/Underpressure trip points.
Function will be very simple, D2 Gas will be generated by PEM Cell and keep in small vessell under overpressure max. 1100 mBar a, above this pressure D2 will be gently vented by solenoid valve with flow reducer and sintered filter. In normal function, Gas flow will be reduced by precise neeedle valve to Fusor chamber, there is possibilty to reduce generation of D2 by PWM PEM Cell control to avoid overpressure. And if acidentally decrease the pressure below 900 mBar a vent valve will be opened to avoid destroy PEM cell by this low pressure. I get a professional Peltier cooled cold trap (3.stage/-45°C), so this is reason why is used there.

Further description and block schematic is attached.

I would like to welcome any comments, mainly Iam not sure about min./max. pressure and overall function.

Many Thanks
Best Regards
Martin
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Richard Hull
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Re: PEM fuel cell deuterium generator

Post by Richard Hull »

The rebirth and commentary on this old 2014 posting is often seen in other posts. The rather complex system posted just above in 2021 is a nice exposition on what might be a superior system using a PEM cell.

However, for those not so well disposed to a complex system, a most miraculous system of rather great simplicity and used to create fusion far beyond the norm is presented in a FAQ in this forum!! This is the work of the dedicated Mark Rowley here at fusor.net, and In my estimation is one of the finest FAQs ever created due to its simplicity and its attention to detail coupled with solving in a simple and easy manner the often difficult issue for the amateur in obtaining deuterium gas for use in a fusor.

The amazing thing is that a full video exposition consisting of 3 videos will explain it all! This reduces the effort of PEM cell production of Deuterium gas in a highly successful fusion system to a "monkey-see-monkey-do" experience. Mark tells of how the produced gas is "not wet" and drying not absolutely needed! If drying was needed, Mark's large fusion numbers using his undried gas would not be possible.

This amazing FAQ can be seen and explored at.......

viewtopic.php?f=24&t=13995

Sit down and watch the videos in order. Take notes. Again, the beauty of Mark's system is its simplicity, low cost and proven workability to solve what is often a stumbling block on the road to amateur fusion.

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Jim Kovalchick
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Re: PEM fuel cell deuterium generator

Post by Jim Kovalchick »

I am one of the beneficiaries of Mark's simply design. I have made many neutrons with PEM generated deuterium gas.

I tried to improve upon Mark's design by keeping the piping to both the cell and my fusor piping connected with isolation valves. I found that any little leakage of the shutoff created too much negative pressure on the cell and actually pulled water from the O side to the H side and into my fusor leak valve. Fortunately, I was able to dry my cell out, and it works perfectly again.

One tiny refinement I made was the addition of a second syringe in parallel, to add time to activation runs.

Regarding an isolated system with a PEM, it is key to prevent buildup of too much differential pressure across the membrane. The oxygen side will need to pressurize as much as the deuterium side. In Mark's design, the differential is only enough to push the syringe plunger. I would not assume the membrane can hold much more than that.

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Richard Hull
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Re: PEM fuel cell deuterium generator

Post by Richard Hull »

Mark noted that with use, the syringe might stick a bit and he suggested giving it a tiny pull on occasion as generation proceeds to relieve the pressure. (do not pull deliberately hard to extract! Just assist the natural pressure to move the plunger...Let the natural pressure move the plunger with a tiny assist.)

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: PEM fuel cell deuterium generator

Post by Martiname »

Hi Guys,

OK, It looks like that I little overcomplex this system :-) .
Based on latest comments is theoretically needed same overpressure release system to Oxygen side as well with another pressure switch or diff. measurement.

Thanks
Martin
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Re: PEM fuel cell deuterium generator

Post by russssellcrow »

Dallas Makerspace effort at a PEM Deuterium generator from D2O (99%, source Sigma Aldrich), with a stacked Peltier chiller/dryer, and Web enabled control.

The controller is an Heltec ESP32 programmed in Arduino IDE, with Wifi, and a custom driver board. You can see the Web interface and the Sigma Delta (more resolution than PWM) pulses to the outputs (there are 3; Peltier base, Peltier stack, and PEM). We will add a thermocouple input later for Temp monitoring. D2O freezes in the chiller at 38'F, but we drive it down till the brass chiller gets frosty on the outside.

The two acrylic pressure vessels are a 25um filter (with actuated drain below to recover condensed D2O) and a 0.1um (green) filter to prevent any liquid incursion.

This runs at atmospheric pressure, and connects to the Mass Control Valve, which isolates the Fusor intake manifold. The MFC (another subject post) allows us precision control of Fusor chamber pressure to +/- 1 micron, from 5 to about 200 micron pressure.

We didn't build this unit from scratch. It is a repurposed chiller/dryer from the air bearing Spinner of a Heidelberg PrimeSetter. We added the PEM cell/plumbing, an extra Peltier stack (to double Temp differential to ~120'F), the ESP32 control, and custom electronics to drive it all.
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Dennis P Brown
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Re: PEM fuel cell deuterium generator

Post by Dennis P Brown »

A lot to follow and as someone not readily involved with these types of projects (like many people who read the forum) could use some clarification. Acronyms are useful jargon for people in the know but for others (like myself) rather confusing when reading a post. Please define all such in a post when used for the first time. I assume MFC is mass flow control but in the previous sentence you use mass controller valve; also, how do you get the dryer units purged so they have pure D2?

For us not up on programable devices, what a Heltec ESP32 is or used for would be useful. Yes, google is our friend but a sentence or two.

Labels on the pics would be extremely useful to explain what we are seeing and/or why. I think I see the PEM cell but is it? The dryer 'tanks' - there are two, why? Or are they something else? I assume you are displaying logic outputs in the one pic but but what are they controlling (D2 gas into the fusor, or water into cell, or gas into dryer or all of these) and how are these pulse outputs values controlled and what are they controlling?

Rather lost on why you would even get near the freezing point of heavy water or chill it close to that temp in a unit - is there a purpose? What volume of heavy water does the unit require and what amount of deuterium gas does it produce and how long does it take to produce a specific volume (at standard temperature/pressure (STP))?

Glad for your reporting on a rather advanced deuterium gas generator but would like to follow the post better.
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Richard Hull
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Re: PEM fuel cell deuterium generator

Post by Richard Hull »

Just a thought related to Jim's overpressure comment on the PEM cell's membrane. Maybe Mark Rowley might speak to this idea.

Would a syringe on the O2 side help to balance or lessen that pressure differential during operation?? it might need to be a bigger syringe volume for O2

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: PEM fuel cell deuterium generator

Post by russssellcrow »

Hey Dennis, thanks for the feedback! Since everyone here comes from a disimmilar background, it is useful for the group.

I think you understand that a mass flow controller (MFC) is a mass control valve, it regulates admittance of D2 gas to the chamber. This is understood.

As to the whole Arduino scene, this changes everything. Arduino has layed open computer control to the masses. Where we used to control systems with FPGAs, ASICS, or RTOS (Google this), everyone can now code a program (or download it) and run just about anything they want.

In your interest, I shall label the pics in a future post. The adaptation of existing hardware is rather clever...

As to why we go to all this trouble to freeze Deuterium Oxide; when you electrolyze D20 across a Proton Exchange Membrane (PEM), the membrane doesn't prevent Heavy Water from evaporating across the membrane. We are condensing the Heavy Water from the D2 stream, and recovering most anything which leaks. So far we collecting about 3% of the D2O which is electrolyzed.

I shall post the schematics and code into the Control & Instrumentation section soon.
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Re: PEM fuel cell deuterium generator

Post by russssellcrow »

As per Dennis request, I diagrammed the PEM Electrolyzer Dryer, and included my notebook schematics (which are mostly current). I'll post the Arduino Code in the Control and Instrumentation directory, should anyone want to utilize it.
PEM_Electronics_BlockDiagram.jpg
The PEM cell is driven in Delta Sigma timebased pulses, determined by the User setting on the Web page. How do you get the Web page?
1. Enter your Wifi's Name and Password in the header of the Arduino Code, then compile and upload it to the Heltec, it will attempt to attach on Boot Up.
2. When the Heltec attaches, it will display the IP Address it has been assigned by the DHCP of your WiFi Router.
3. Use this Address to access the Heltec's Web page in most browser's address bar at the top: i.e. \\192.168.1.137

The following is the schematic. The N-chan MOSFETs you use need to be rated for 10Amps and >50V. IRF520 will work fine, so will many others you may have laying about. Opto Isolators are pretty universal too as long as they have Darlington or MOSFET outputs they should work.
PEM_Electrolyzer_Dryer_Schematic.jpg
These are the labelled pics of the PEM Electrolyzer. Dennis asked how I know it's making Deuterium, you test it with Water first. The Hydrogen stinks and the Oxygen smells sweet (also the ports and polarities are marked, it's hard to get wrong) I changed the plumbing of the bottom ports of the PEM cell, so we can fill both sides from 1 port and have a shutoff valve.
PEM_Electrolyzer_Dryer_front.jpg
PEM_Electrolyzer_Dryer_rear.jpg
Operation is pretty easy:
1. Fill the PEM with D2O, and push a little extra so it just barely shows in the O2 and H2 vent ports. When you start the process, this will push a small Marker Bubble up the lines so you can see the flow rate. It also makes a liquid wall to keep the Deuterium Gas from being mixed with the air in the system. Don't worry about the bubble, it will drop into the trap at the 1st filter vessel for capture.
2. Use the Web page to drive the Chiller through the dual Peltier Controls. We found that about 10 on each Setting will take the Chiller cube down to where it frosts on the outside. If you overdrive the Peltiers, the Chiller can go to -60'C which is way too cold.
3. Next start the PEM cell on the Web page. A Setting of about 12-15 here will make your D2O bubble move along pretty well toward the filters, about 1 inch/5 seconds. 2 inches of 4mm tubing full of Deuterium (6.28 mm^3) at Standard Atmospheric pressure is enough fill ~150cc at 30 microns.
4. We ran the Fusor vaccum until we hit <5 microns of pressure, and then actuated the Mass Flow Controller, MFC (another post yet to come, with schematics and code). Then we balanced the pressure to 30 microns using the MFC Web page, with a setting of about 25%.

We still have a lot of work to do to go operational. We have begun work on Fusor #2, because it's time to light this thing up for real, but that is a different post.
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Re: PEM fuel cell deuterium generator

Post by Richard Hull »

Elaborate in the extreme, for sure. As long as you have heavy water, you have flawlessly clean, dry and pure D2 for fusion. Great work!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: PEM fuel cell deuterium generator

Post by russssellcrow »

Elaborate...looks pretty straightforward, you wouldn't believe some of the hoops I jump through in my day job.

But seriously, the issue you brought up with overpressuring the PEM membrane in this cell is real. On this cheap PEM cell, I would wager that the membrane can't push more than 1/2 Bar, with that comes heavy water vapor and Oxygen in the D2 stream. By comparison a Plug Power Cell can push about 10 Bar of differential pressure. Since the membrane is very critical to isolation, the next upgrade to this component will be the PEM cell.

In the meantime, we have decided it is time to take heed to your warning and build a serious Fusor. We've seen what we needed to in our see through filter cylinder (I just inherited it), and started collecting some serious hardware. See the post titled Fusor2_DMS, this is getting so much better!
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